Polyglutarimides are acrylic-glutarimide copolymers containing units of the structure: ##STR1## where R.sub.1 and R.sub.2 are H or methyl, and R.sub.3 is hydrogen, alkyl, cycloalkyl, substituted alkyl, substituted cycloalkyl, aryl, substituted aryl, alkaryl, substituted alkaryl, aralkyl, substituted aralkyl, or heterocyclic. Polyglutarimides (especially those polyglutarimides where R.sub.1 and R.sub.2 are CH.sub.3 and R.sub.3 is H or methyl), are useful thermoplastics, exhibiting thermal stability, moldability, clarity, low color, reasonable toughness, and good barrier properties. It has further been known that such polyglutarimides, especially those where acid or anhydride groups present in the polyglutarimide are reacted with an alkylating or esterifying agent to reduce the acid/anhydride content to levels of about 0.5 weight percent or less, are compatible with a broad variety of thermoplastics, as well as serving as compatibilizers for blends of many polar polymers. Polyglutarimides, sometimes hereinafter referred to as imides or PGI, are prepared by imidizing acrylic polymers. See U.S. Pat. No. 4,727,117 for one method of preparing PGI's having acid and anhydride content lower than those prepared by U.S. Pat. No. 4,246,374. The disclosures of both U.S. Pat. No. 4,246,374 and U.S. Pat. No. 4,727,117 are incorporated by reference herein. From time to time in this specification, the phrase "capped imides" or "capped PGI's" will refer to those imides made by the process described in U.S. Pat. No. 4,727,117.
It is known that PGI's can be blended with a wide variety of other polymeric materials. For example, see TABLE XVII and XX, column 34 and 35 in U.S. Pat. No. 4,727,117 where PGI's are blended in a series 50/50 weight blends with many thermoplastic blends including some polyesters that may or may not be considered semi-crystalline, (i.e. PETG). Among the polar polymers are included polyesters, especially aromatic polyesters, by which is meant the polymer formed by condensation of an aliphatic glycol with an aromatic acid, such as ethylene glycol with terephthalic acid, commonly known as poly(ethylene terephthalate) (PET), or butylene glycol with terephthalic acid also known as poly(butylene terephthalate) (PBT), and the like.
Liquid crystalline (LC) polyesters are typically made from monomers of aromatic diols, aromatic diacids and aromatic hydroxy acids and other monomers having ring structures capable of giving a stiff chain with high axial aspect ratio. Aromatic diols and the like are represented by: ##STR2##
The aromatic diacids and the like are represented by: ##STR3##
The aromatic hydroxyacids and the like are represented by: ##STR4##
Hydroxyacetamides are represented by ##STR5##
In some of the above formulas, X and Y may represent hydrogen, halo, sulfur and lower alkyls of up to about 4 carbon atoms.
Another polymer that can be blended with the polyglutarimide polymers include the benzimidazoles (BI).
The polybenzimidazoles (PBI) consist essentially of recurring units of the following Formulas I and II.
Formula I is: ##STR6## wherein R is a tetravalent aromatic nucleus, preferably symmetrically substituted, with the nitrogen atoms forming the benzimidazole rings being paired upon adjacent carbon atoms, i.e., ortho carbon atoms, of the aromatic nucleus and R' is a member of the class consisting of (1) an aromatic ring, (2) an alkylene group (preferably those having 4 to 8 carbon atoms), and (3) a heterocyclic ring from the class consisting of (a) pyridine, (b) pyrazine, (c) furan, (d) quinoline, (e) thiophene, and (f) pyran.
Formula II is: ##STR7## wherein Z in an aromatic nucleus having the nitrogen atoms forming the benzimidazole ring paired upon adjacent carbon atoms of the aromatic nucleus.
Preferably, aromatic polybenzimidazoles (PBI) are selected from polymers consisting essentially of the recurring units of Formulas I and II wherein R' is an aromatic ring or a heterocyclic ring.
U.S. Pat. No. 3,174,947 and Re. U.S. Pat. No. 26,065, teach that the aromatic polybenzimidazoles having the recurring units of Formula II are prepared by selfcondensing a trifunctional aromatic compound containing only a single set of ortho-disposed diamino substituents and an aromatic, preferably phenyl, carboxylate ester substituent. Exemplary of polymers of this type is poly-2,5(6)-benzimidazole prepared by the auto-condensation of phenyl 3,4-diaminobenzoate.
As set forth in the above-mentioned patents, the aromatic polybenzimidazoles having the recurring units of Formula I may be prepared by condensing an aromatic tetraamine compound containing a pair of orthodiamino substituents on the aromatic nucleus with a dicarboxylic compound selected from the class consisting of (a) the diphenyl ester of an aromatic dicarboxylic acid, (b) the diphenyl ester of a heterocylic dicarboxylic acid wherein the carboxyl groups are substitutents upon a carbon in a ring compound selected from the class consisting of pyridine, pyrazine, furan, quinoline, thiophene and pyran and (c) an anhydride of an aromatic dicarboxylic acid.
The liquid crystalline polyesters (LCP) within the scope of this invention are those polymers usually involving a succession of para-oriented ring structures to give a stiff chain with high axial aspect ratio (ratio of length of molecule to its width. Liquid crystalline polyesters (LCP) or copolyesters (LCP) used in the blends of this invention may also contain "spacer" groups to interlink the low molecular weight monomers. The spacer groups may be, for example --(CH.sub.2).sub.n --. Other spacer units include the following: ##STR8## and various combinations thereof where n may be from 1 to 16.
The LCP field has expanded rapidly in the last few years with the development of various copolymers of 6-hydroxy-2-naphthoic acid (HNA), 4-aminophenol, and terephthalic acid. Liquid crystal (LC) domains form stiff rodlike molecular alignment that occurs in a preferred direction along their long axes. The synthetic aramids such as poly(1,4-benzamide) (PBA) and polyazomethines set the stage for developing blends with other melt processable thermoplastics. It is believed liquid crystalline nature is the consequence of molecular symmetry shape and chain stiffness.
These repeating units for LCP can be found in such well recognized products as VECTRA.RTM., KEVLAR.RTM., XYDAR.RTM. and others. The LCP's will increase the tensile strength, heat resistance distortion improvement and other properties when blended with the polyglutarimides (PGI) in relatively small amount. When the LCP's are blended with PGI lower viscosities than the pure imides result. Therefore, the processing of these blends will be relatively easy by injection molding. Other improved properties may include enhanced flame retardance, lower coefficient of linear thermal expansion, and greater chemical resistance to solvents. Such PGI/LCP blends as described and claimed herein will find use in many different applications such as compatibilizing agents, modified thermoplastics and impact modified thermoplastics, toughening agents, tie layers in multilayer coatings, processing aids, adhesives, coatings, oriented films, such as biaxially oriented blown films and engineering thermoplastics.